The present invention relates to a knee area protection apparatus for a vehicle occupant which comprises an air bag sack, inflatable upon deployment, which is held ready in its non-deployed condition behind a covering at a location in the foot area of the vehicle seating compartment or the lower region of the instrument panel of the vehicle. The air bag sack is of the type that, upon its inflation during deployment, effects the release of the covering relative to a support plate which normally retains the covering in its covering position in the non-deployed condition of the air bag sack. The deployment movement of the air bag sack moves the covering in the direction of the knee area of the seat occupant and a plurality of retaining, guiding, and positioning straps, whose slack is taken up by the movement of the covering, guide the covering into, and retain the covering in, its final position.
A knee area protection apparatus of the type just described is disclosed in EP 0 885 783 A1; the disclosed knee area protection apparatus has a substantially right-angled cover which assumes the role of a deployment guiding plate upon the deployment of the air bag sack and which is retained via four retaining bands extending between and connected to the cover and a support plate. The length and the connection location of each retaining band is configured such that, during the deployment movement of the cover due to the inflation of the air bag sack (during which the cover assumes its role as a deployment guiding plate), the deployment guiding plate experiences an upward movement or a descending movement relative to the fixedly mounted support plate or, respectively, the instrument panel of the vehicle. The four retaining bands are arranged respectively in the area of the vertically extending side edges of the deployment guiding plate such that (1) these retaining bands engage the sides of the inflating air bag sack, as a result of which the coupling of the retaining band secured in the area of the top transverse edge of the deployment guiding plate is shifted downwardly in the vertical direction by a predetermined amount, (2) this retaining band adjacent the top edge assumes a diagonal course in the initial phase of the unfolding of the air bag sack and (3) the retaining band, once its slack is taken up, acts to effect the upward movement of the deployment guiding plate. In accordance with an embodiment of this known knee area protection apparatus, it is in any event provided that the retaining bands, which are arranged in a vertical series relative to one another, are each respectively formed as a single piece and each of these individual single length retaining bands is trained from its connection at the top transverse edge of the support plate through an opening in the deployment guiding plate, from there across the outer surface of the deployment guiding plate in a downward direction, thereafter through another opening, and finally to its connection at the bottom transverse edge of the support plate.
The known knee area protection apparatus still bring with them the disadvantage that may occur when, as a result of the differing lengths of the individual retaining bands during the unfolding of the inflating air bag sack and the shifting course of movement of the deployment guiding plate during this unfolding, the deployment guiding plate reaches a non-final tilted position from which it is then drawn backward in a correcting movement into its final position as the retaining bands use up their slack and become fully extended. In this event, if the deployment guiding plate, upon reaching this non-final tilted position, is already in contact with the knees of the seat occupant, it cannot be ruled out that the seat occupant may be injured. A further disadvantage resides in the fact that it cannot be foreclosed that, in such a tilted position of the deployment guiding plate, the air bag sack will press upwardly or downwardly through the open space between the support plate and the deployment guiding plate, whereby this air bag sack bulging movement can additionally impact the position of the deployment guiding plate.
The present invention offers a solution to the challenge of providing a knee area protection apparatus which is so configured that, at each point in time during the unfolding of the inflating air bag sack, the movement of the deployment guiding plate of the knee area protection apparatus being driven by the air bag sack inflation occurs continually along a prescribed movement path into the final position of the deployment guiding plate.
The present invention provides, in accordance with its core concept, a knee area protection apparatus comprising a pair of retaining bands extending substantially vertically, each between a respective side edge of the support plate and a side edge of the deployment guiding plate with each retaining band being engaged at the upper region of the support plate and the lower region of the deployment guiding plate such that the retaining band assumes a diagonal course upon inflation of the air bag sack and engages the air bag sack along its side, and further comprising a pair of retaining bands each extending between the regions of the support plate and the deployment guiding plate bordering on the top transverse edges thereof and between the regions of the support plate and the deployment guiding plate bordering on the bottom transverse edges thereof with the connections of these pair of retaining bands to the support plate and the deployment guiding plate being configured such that these further pair of retaining bands assume diagonal courses upon inflation of the air bag sack and engage the air bag sack along its top and bottom. In contrast to the known knee area protection apparatus, the number of segments of the retaining bands of the knee area protection apparatus of the present invention between the support plate and the deployment guiding plate is increased from four to six so that the air bag sack is now engaged by the retaining bands from top and bottom as well. In this manner, a definitive guiding of the deployment guiding plate during its movement away from the support plate is ensured. Only one respective retaining band is arranged on each side edge of the support plate and the deployment guiding plate of the knee area protection apparatus of the present invention while, in the regions of the top and bottom edges, respective pairs of the retaining bands, or respective pairs of segments of the retaining bands, are provided.
In accordance with one embodiment of the knee area protection apparatus of the present invention, it is provided that, in connection with the retaining bands which interconnect, respectively, the top transverse edges of the support plate and the deployment guiding plate and the bottom transverse edges of the support plate and the deployment guiding plate, the retaining bands on the same respective side of the high axis of the knee area protection apparatus are arranged such that those portions thereof extending between the bottom transverse edges of the support plate and the deployment guiding plate have diagonal courses which are linear extensions of the diagonal courses of the portions of the retaining bands extending between the top transverse edges of the support plate and the deployment guiding plate. In this manner, the retaining bands or the portions thereof extending diagonally over the front surfaces of the deployment guiding plate have an overall V-shaped profile.
While the knee area protection apparatus of the present invention can be configured alternatively with separate side retaining bands for two respective sides of the support plate and the deployment guiding plate, in accordance with one embodiment of the knee area protection apparatus of the present invention, it is provided that a single retaining band comprises both side segments and that the single retaining band is trained through openings in the deployment guiding plate and has a portion extending between the openings along the respective face of the deployment guiding plate which faces away from the support plate. In this arrangement, the openings for the training therethrough of the side segments of the single retaining band are located high up toward the corners of the deployment guiding plate parallel to the side edges of the deployment guiding plate.
It can be provided that the portion of the single retaining band extending across the face of the deployment guiding plate is secured at at least one location to the deployment guiding plate.
Along the same lines as the single piece retaining band embodiment of the knee area protection apparatus of the present invention, it can also be provided, in accordance with one embodiment of the knee area protection apparatus of the present invention, that a single retaining band comprises both of the pair of segments trained through and along a respective side of the deployment guiding plate, whereby one segment of the pair extends between the top transverse edges of the support plate and the deployment guiding plate on one side thereof and the other segment extends between the bottom transverse edges of the support plate and the deployment guiding plate and is a linear extension of the other segment of the pair in that the single retaining band is (1) trained through openings in the deployment guiding plate which are arranged in vertical series with, and at a horizontal offset to, one another and (2) extends along the face of the deployment guiding plate away from the support plate. In this manner, each of the two single retaining bands form an overall V-shaped profile.
It can be provided that each of the single retaining bands forming the side retaining band segments can be secured at at least one location to the deployment guiding plate. The securement between the retaining bands or, respectively, the segments of the retaining bands, and the deployment guiding plate can be accomplished by a rivet.